1. Field of the Invention
The present invention relates to a radiation imaging apparatus, radiation imaging method, radiation image processing apparatus, radiation image processing method, and computer-readable storage medium.
2. Description of the Related Art
In the field of image diagnosis using radiation imaging apparatuses and more particularly X-ray imaging apparatuses, an image intensifier (to be also referred to as an “I.I.” hereinafter)-TV system has been widely used. Recently, there has been proposed a radiation imaging apparatus using a solid-stage radiation (for example, X-rays) detector with a high resolution which uses an FPD (Flat Panel Detector) in place of an image intensifier. A captured image obtained by an I.I. is circular. In contrast, a radiation imaging apparatus using an FPD allows to increase the effective field of view as compared with an I.I. because the FPD is a quadrangular flat panel detector (having, for example, a rectangular shape).
In a radiation imaging apparatus using a conventional I.I., even when the detector unit rotates or an image on the display device rotates, since the radiation irradiation region to be displayed has a circular shape, the rotation does not change the effective display region. That is, no problem has arisen. For example, Japanese Patent Laid-Open No. 2000-217808 discloses an invention which copes with the rotation of a detector by using a display rotation system to rotate a TV monitor. Matching with the image reception area of a radiation irradiation field is defined by an industrial standard in “JIS Handbook 2005 Radiation (Activity)”, C0601-1-3 medical electrical equipment: Japanese Standards Association, section 29.203.4 and FDA Part 1020 Sec. 1020.32 Fluoroscopic equipment.
However, the radiation imaging apparatus using the above FPD has the following problems.
FIG. 2A shows a case in which a quadrangular flat panel detector performs display operation so as to match the vertical and horizontal directions of an image display region on a display device with those of the quadrangular flat panel detector. An image 201 is the radiation image detected by the quadrangular flat panel detector. An auxiliary view 202 represents the relative positional relationship between the object and the quadrangular flat panel detector. In this case, depending on the positional relationship between the object and the quadrangular flat panel detector, the user may want to display an image upon rotating it. For example, referring to FIG. 2B, the auxiliary view 202 is obliquely displayed. This occurs when, for example, the relative positional relationship between the object and the quadrangular flat panel detector has an error or the vertical and horizontal directions of the quadrangular flat panel detector do not match those of the display device. At this time, if, for example, as shown in FIG. 2C, the image is rotated to an orientation that allows easy observation while the display magnification of the image is maintained, there are some regions which are not displayed on the display device. That is, there is a possibility that the image data detected by the quadrangular flat panel detector may be partly lost by rotating operation. In order to prevent such data loss, display conditions need to be adjusted as shown in FIG. 2D.
In general, a radiation imaging apparatus is provided in advance with a mode of storing captured images and a mode of storing no image. For example, in an imaging mode called fluoroscopy, no captured image is stored in the imaging apparatus. On the other hand, in imaging modes other than fluoroscopy, for example, the serial radiography and cine modes, all types of images are targets to be stored. The mode of storing no image is used for a postoperative checkup on a patient after surgical operation or positioning or timing adjustment for still image capturing. This mode is rather a mode of checking an image on the spot. In contrast, each mode of storing images is often used for the purpose of performing detailed diagnosis afterward by using stored images. As described above, in the mode of storing no image, the user wants to display the entire radiation irradiation region, and hence wants to avoid the loss of part of image data by rotating operation. In contrast, in the mode of storing images, since the user wants to continuously display a region of interest on the screen, the user wants to easily check the region of interest. That is, the timing and contents of image checking operation differ depending on the purpose of imaging. For this reason, setting the same conditions for deciding an image display form such as rotational display, enlarged/reduced display, panning display (display with movement of image center), or the like makes it difficult to obtain a desired observation image.
In consideration of the above problems, the present invention provides a technique of displaying the radiation image captured by using a quadrangular flat panel detector in a display form corresponding to each purpose of imaging by controlling the display form of an image in accordance with each purpose of imaging in the imaging mode of storing images and the imaging mode of storing no image.